Folded steel plate girders are commonly used in constructing bridge spans. These types of girders are advantageous for short bridge spans of 60 feet or less, which accounts for about half of the almost 700,000 bridges in the United States. Folded steel girders provide a quick, cost-effective system for building new, short span bridges and for repairing existing ones. The folding process forms an open channel in the girder that traverses the length of the bottom side of a folded plate girder. This channel allows for quicker and easier inspection, which can also save costs.
Folded steel plate girders are limited to short span bridges or simple spans. Longer bridges and those intended to support greater weights are designed to have a certain amount of camber. Camber is an obtuse curvature in a long span that helps to absorb weight near the center of the span and increase strength. Because of the method by which folded steel plate girders are manufactured and the final shape of the girders, it is not possible to introduce camber into the girder. This limits the applicability of folded steel plate girders.